Spin-isospin resonances with the new functionals: SAMi, SAMi-ISB and SAMi-T.

Résumé

In this seminar, I will review some recent developments of the Milano group in the
study of spin-isospin resonances with Skyrme functionals.
In the past, different attempts to build a functional that can describe nuclear masses,
charge radii and excitation energies of non-charge exchange and charge exchange
resonances at the same time have been performed [1-4]. On this regard, we have
proposed in Ref. [5] a new functional named SAMi based on a fitting protocol that
allows for a better description of spin-isospin resonances without compromising the
accuracy in the description of other observables. Subsequently, in Ref. [6] we have
further improved the SAMi functional by including tensor terms. For that, we have
kept the same fitting protocol of SAMi but including also information from ab initio
calculations on neutron and neutron-proton drops to determine the tensor terms.
The new functional has been named SAMi-T. In parallel to the latter work, we
have also improved the SAMi functional in the description of the Isobaric Analog
State (IAS), a pure isospin resonance. Such improvement has been achieved by
the inclusion of isospin symmetry breaking terms to the functional [7]. The new
interaction is named SAMi-ISB. In this case, the SAMi fitting protocol has been
extended to also include information on ab initio results of ISB corrections to the
symmetric matter equation of state and of the IAS in $^{208}$Pb.\newline
[1] N. Giai and H. Sagawa, Phys. Lett. B 106, 379 (1981).\newline
[2] P.-G. Reinhard, D. J. Dean, W. Nazarewicz, J. Dobaczewski, J. A. Maruhn, and
M. R. Strayer, Phys. Rev. C 60, 014316 (1999).\newline
[3] N. Paar, T. Niksic, D. Vretenar, and P. Ring, Phys. Rev. C 69, 054303 (2004).\newline
[4] H. Liang, N. Van Giai, and J. Meng, Phys. Rev. Lett. 101, 122502 (2008).\newline
[5] X. Roca-Maza, G. Colò and H. Sagawa, Phys.Rev. C 86, 031306 (2012).\newline
[6] Shihang Shen, G. Colò and X. Roca-Maza, arXiv:1810.09691 (2018) (Submitted
to PRC)\newline
[7] X. Roca-Maza, G. Colò, and H. Sagawa, Phys. Rev. Lett. 120, 202501 (2018)